1. Field of the Invention
The present invention relates to a packaging board and a manufacturing method therefor, a semiconductor module and a manufacturing method therefor, and a portable device.
2. Description of the Related Art
In recent years, along with the on-going downsizing and functional sophistication of electronic devices, there has been an ever-growing demand for smaller circuit devices to be incorporated into electronic devices. One of known ways to meet such a demand is to narrow the pitch of external connection electrodes of a circuit device. But because of the size of solder bumps themselves used as the electrodes and the formation of bridges at soldering, there has existed a limit to the downsizing by narrowing the pitch of the external connection electrodes of a circuit device. For further downsizing of a circuit device, therefore, there is a technology conceived for rearrangement of external connection electrodes by forming a rewiring for a circuit device.
In general, when the rewiring is formed in the circuit device, an opening by which to provide a via contact for an insulating layer on an electrode pad is formed in order to retrieve externally a signal sent from a circuit element within the circuit device via the electrode pad. In the conventional practice, a method is conceived where the formation of such an opening is done by laser irradiation. However, since the circuit element is placed below the electrode pad, it is desired that such an opening be formed without being exposed to high temperature as much as possible. As one of known methods to resolve this problem is a method for manufacturing a semiconductor device by the laser irradiation followed by dry etching.
Nevertheless, in the above-described method, the electrode pad exposed at the final stage in the dry etching is exposed to plasma atmosphere while the effect of heat by the laser irradiation can be suppressed. As a result, the circuit elements, such as transistors, which are connected to the electrode pad may possibly be charged up. Accordingly, the device performance deteriorates due to the charge-up phenomenon and therefore the reliability of circuit elements drops.